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Question regarding electrical power sources

Started by AAnnillo, February 18, 2021, 08:59:20 AM

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I have acquired a 115VAC 400Hz power inverter.
Its the KGS Electronics model SPC-30.
There are seven (7) wires in the plug:

A - Input +28VDC
B - Output 115VAC
C - AC Return (Com)
D - DC Ground
E - Remote On & Off
F - Osc. Sync. Out
G - Output 26VAC

I've fired it up with a 28VDC power supply in the A and D wires and got that lovely 400Hz high pitched sound that we're familiar with.

My question is this:

What is the AC Return (Com)?   I'm assuming the (Com) is shortened for 'common' but cannot validate this.  If it is, would it be safe to assume that its actually the AC Ground as there is nothing listed for AC Ground...just the DC Ground.

Given my limited knowledge of electronics, my assumption is that it would be a ground as the instrument/wiring manuals I've seen do not show a ground, just this AC Return...and only in regard to the power inverter.  Also, on that subject, is it possible/advisable to use a 'common ground' for 5V/26V/28V AC/DC or would you suggest using separate grounds based on current and voltage types?

Thank you for helping to shed some light on this topic.

I appreciate your input.



My 737-800 full-scale cockpit has been sold. Now onto my full-size military helicopter project. An AOPA member and LifeTime member of National Association of Flight Instructors. Please note that I am a self-employed professional cockpit builder that provides consulting to defense contractors and civilian schools and airlines.


Thank you for the reply.

I had seen that schematic on the KGS Electronics website as well.

Based on that, it would be safe to assume the 'common' is actually an AC-Ground...unless my understanding is incorrect.

Thank you!!


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